Applications employing wireless devices require low power analog circuits, powered by low voltages (for example, of about 1.5 V) and having maximum integration.
A commercially available device includes a phased-locked loop fitted with a voltage-controlled oscillator. The oscillator has a ring structure that includes a number of delay cells looped together. Its nominal oscillation frequency is 2.45 GHz. A transistor of the oscillator that operates as a current source is used to define its oscillation frequency.
An oscillator of this kind does, however, have drawbacks. For example, during an emission phase, the phased-locked loop can be open. The oscillation frequency then drifts to a value defined by external parameters, such as the temperature.